Trivalent lanthanide complexes of the type K[ML₂] whereM=La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III) and Dy(III) and H₂L=N-isonicotinamidosalicyladimine, have been prepared and characterised. The nephelauxetic ratio (β), covalency (δ) and bonding parameter (b²) of K[NdL₂] have been calculated. Infrared spectral studies reveal that N-isonicotinamidosalicylaldimine acts as a dibasic tridentate ligand. A coordination number six has been proposed for the lanthanide metal ions.

Tyrosine hydrazide (TH) has been found to form complexes of the types [M(TH)₃Cl₂]Cl [M=La(III), Pr(III), Nd(III)] and [M′(TH)₂Cl₂]Cl [M′=Sm(III), Eu(III), Gd(III) and Dy(III)]. The complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared, electronic and PMR spectral studies. The nephelauxetic ratio (β), covalency (δ) and bonding parameter, (b^1/2) of [Nd(TH)₃Cl₂]Cl have been calculated. Infrared spectral studies reveal that TH acts as a neutral bidentate ligand. Coordination numbers of eight around La(III), Pr(III) and Nd(III) and six around Sm(III), Eu(III), Gd(III) and Dy(III) have been proposed in the complexes.